A new, efficient, and practical radical cyclization of olefinic amides with ketones through α-C(sp3)–H functionalization in the presence of tert-butyl peroxybenzoate (TBPB) is described for the first time. This protocol assembles a wide range of pivotal and useful benzoxazines in good to excellent yields under mild, catalyst-free, ligand-free, and base-free conditions with wide functional group tolerance
Treatment of Olefinic Amides with NBS in Water: Synthesis of Monobromo- and Multibromobenzoxazines
作者:Xu Zhang、Wen-Bin Cao、Xiao-Ping Xu、Shun-Jun Ji
DOI:10.1055/s-0037-1610724
日期:2019.10
Abstract Treatment of olefinic amides with N-bromosuccinimide (NBS) in water is reported. Monobromobenzoxazines were mainly formed at room temperature, while at 80 °C multibromobenzoxazines were preferentially generated. Mechanism studies showed that the reaction might proceed via a cascade of electrophilic addition at the C=C bond followed by electrophilic substitution at the aromatic ring. No additives
Synthesis of 4-cyanoethylated benzoxazines by visible-light-promoted radical oxycyanomethylation of olefinic amides with bromoacetonitrile
作者:Song Sun、Cong Zhou、Jiang Cheng
DOI:10.1016/j.tetlet.2019.07.017
日期:2019.8
A facile and efficient protocol for the visible-light-promoted radical oxycyanomethylation of olefinic amides with bromoacetonitrile has been developed, affording a series of 4-cyanoethylated benzoxazine derivatives in moderate to excellent yields. The reaction featured with diverse functional group tolerance and mild reaction conditions.
Palladium-Catalyzed Cyclization of Alkenes with Organohalides
作者:Xue-Qiang Chu、Dan Liu、Zhen-Hua Xing、Xiao-Ping Xu、Shun-Jun Ji
DOI:10.1021/acs.orglett.6b00035
日期:2016.2.19
A palladium-catalyzed tandem C–Br/C–H functionalization and cyclization of alkenes with organohalides is reported. This reaction provides an operationally simple method for the synthesis of various fluorene, pyrroloindole, and benzoxazine derivatives, which are useful pharmaceutical framework and photoelectronic devices. Two new C–C/O bonds, a quaternary carbon center and a new ring, are simultaneously
Transition-Metal-Free Oxyfluorination of Olefinic Amides for the Synthesis of Fluorinated Heterocycles
作者:Jing-Feng Zhao、Xin-Hua Duan、Hua Yang、Li-Na Guo
DOI:10.1021/acs.joc.5b01909
日期:2015.11.6
A series of fluorinated 4H-3,1-benzoxazines and iminoisobenzofurans have been synthesized through the electrophilic fluorocyclization of olefinic amides. This methodology is highlighted by its mild conditions, wide substrate scope, and good functional group tolerance.
通过烯烃酰胺的亲电氟环化反应,合成了一系列氟化的4 H -3,1-苯并恶嗪和亚氨基异苯并呋喃。该方法具有温和的条件,广泛的底物范围和良好的官能团耐受性,从而突出了该方法。